Characteristics of Tibetan Plateau Snow Cover in Winter and Spring and Their Influences on Summer Rainfall over China
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Abstract:
In this paper, based on the data of daily snow depth (SD) and the number of days with snow cover (NDSC) from the National Meteorological Information Center and the atmospheric circulation data from NOAA reanalysis, by using the Empirical Orthogonal Function (EOF) decomposition, composite analysis, and other statistical methods, we examine the interannual and interdecadal variations of winter and spring snows in terms of the number of days with snow cover (NDSC) and snow depth (SD) in the entire Tibetan Plateau, the eastern Tibetan Plateau (ETP), and the western Tibetan Plateau (WTP), respectively, and found that in the past 53 years (1961 to 2013), the temporal trends of winter and spring snows averaged over the entire Tibetan Plateau are general similar. The interdecadal variations of SD exhibit the feature of “lessrichlessrich” than normal,and those of NDSC shows the feature of “lessrichless” than normal. For the temporal trends of snow cover in two regions (ETP and WTP), snows increased significantly in the the 1960s and 1970s and reduced in the 1980s and 1990s for both regions. However, the trends were obviously different since the late 1990s, when the snow cover reduced significantly in the ETP whereas it significantly increased in the WTP except for the spring NDSC that showed no apparent trends. Then we identify the typical years with anomalous snow cover in the ETP and WTP, respectively, and investigate the features of snow cover anomalies and the associated atmospheric circulation anomalies. Finally we investigate the impacts of snow cover anomalies in the Tibetan Plateau on the summer rainfall over China. The results show that significant difference exists in the temporal variations of snow cover for the different regions of the Tibetan Plateau. The results also show apparent correlation between snow cover variations in the Tibetan Plateau and summer rainfall in China. Therefore, it is necessary to take into account the different impacts exerted on summer rainfall by snow cover anomalies in different regions of the Tibetan Plateau when the snow cover in the Tibetan Plateau is used as a factor for the shortterm prediction of summer climate in China.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.